This invention relates to improvements in prostheses for permanent implantation to establish a desired body contour and has particular application and advantages in the area of mammary implants.
Throughout the history of our society, the female breast has been a symbol of femininity and an object of sexual stimulation which has been exploited in the arts, in literature and commercially with the result that women who have undergone mastectomies or whose breast structure may be considerably less or greater than might be desired become enmeshed with many physical, emotional and psychological problems. The rehabilitation of such women has been a prime area of interest by the medical profession and particularly plastic surgeons and since the first attempt at breast reconstruction recorded in 1893, considerable progress has been made and documented in that field and in augmentation and reduction mammaplasty.
Two basic procedures have been developed for breast reconstruction. One procedure, which for purposes here can be described generally as the use of skin and muscle flaps in various forms and arrangements, involves the replacement of tight skin and muscles by muscle and skin transfers and transplantation to produce a suitable breast mound. In the other procedure, the lost breast mound is reestablished by implantation of a prefabricated or customed designed prosthesis. Both procedures have well documented advantages and disadvantages related to varying conditions that may be present in any particular patient considering a choice of procedures. It is with the prosthesis procedure that my invention is directed.
This invention will be preferably described in relation to a mammary implant because of its particular advantage for such purpose. Such type of implant is placed in a surgically created body cavity and filled with a saline solution by well known procedures. Postoperatively, the implant may require the serial addition of saline to effect expansion of the skin, withdrawal of fluid to release pressure or reduce the volumetric content, if necessary, or otherwise addition or withdrawal of fluid as may be required as the implant settles into position and swelling diminishes and, at time, the injection or withdrawal of antibiotics and other additives such as steroids may be required as is well known for the study, management and possible control of capsular constracture which is an incidence of implant procedures. Capsular contracture may be described generally as the collection of fibrous or scar tissue that encapsulates the prosthesis and which must be ruptured or broken when it develops. This can be accomplished by a closed capsulotomy which is external manipulation of the breast tissue that is commonly required and relatively simple for some patients with mammary implants but very difficult for others due to a variety of factors so as to require the use of an anesthetic or by an open capsulotomy that involves surgical procedures.
Breast reconstruction, whether by the skin flap or prosthesis procedure involves initial surgical procedures and by its very nature creates emotional, physical and psychological factors for the patient which are inherent with surgery in general and with breast reconstruction in particular so that it is highly desirable to avoid surgery whenever possible in any postoperative treatment. The development of the injectable prosthesis reflects endeavors to provide a method of performing the postoperative procedures indicated by percutaneous injection to avoid surgery but such devices as presently known have certain disadvantages and drawbacks from the standpoint of efficiency and safety that will be pointed out.
The implantable prosthesis procedure was introduced in the mid-seventies in the form of a temporary expandable envelope connected by an elongated tube to an injectable reservoir. The envelope was placed through an incision into the breast cavity and the reservoir was placed in a small subcutaneous pocket posteriorly to the incision. The envelope was supplied from time to time by percutaneous injection into the reservoir, as distinguished from the envelope, to accomplish gradual stretching of the skin to a desired point at which time it was surgically removed and replaced by a permanent implant. The apparent disadvantage and drawback of this early device is the necessity of an undesired second surgical operation. An improvement in this early method has been the replacement of the temporary envelope with a permanent prosthesis but retaining the injectable reservoir which still requires surgery for removal.
A subsequent development to the implant-reservoir procedure has been the prosthesis designed to postoperatively add or withdraw implant additives by percutaneous injection directly into the prosthesis envelope and thus avoid additional surgery such as exemplified by U.S. Pat. Nos. 4,253,201 and 4,428,364. This type of prosthesis includes a self-sealing valve at a selected point on the anterior surface of the prosthesis and is implanted subcutaneously so that the location of the valve for purposes of injection or withdrawal of fluids can be accomplished by palpation by the surgeon. However, such means for locating the valve is dependent upon the subcutaneous location of the prosthesis where palpation is favorable but in the further development of the mammary prostheses art where the placement of the prosthesis is now predominately submuscularly where the incidence of capsular contracture is considerably less, palpation for locating the valve is, for all practical purposes, extremely difficult, if not impossible at time and therefore quite unreliable. A disadvantage of the prostheses where valve location depends upon palpation is that when a capsular contracture occurs, a closed capsulotomy is necessary to make the valve palpable and when inadequate capsule release results from a closed capsulotomy, an open capsulotomy is necessary to expose the valve.
U.S. Pat. No. 3,919,724 discloses a double envelope prosthesis with a self-sealing anterior valve for percutaneous injection directly into the prosthesis through the valve which has an associated pocket filled with a suitable radiopaque material whereby the valve area can be located by X-ray. The inner envelope is secured posteriorly to the outer envelope and is filled by the injection needle passing through both the outer and inner envelope. However, since the inner envelope is collapsible within the outer envelope, there is considerable danger if the prosthesis is deflated of the outer wall being pierced by the needle and causing leakage.
U.S. Pat. No. 4,253,201 addresses the problem of potential damage to the envelope from the injection needle and discloses a single envelope prosthesis with an anterior self-sealing valve for percutaneous injection with the valve being preferably located by palpation. In this device, a cylindrical body extends into the envelope to form a closed chamber for receiving injected material which passes into the envelope through holes in the chamber. One end of the chamber forms a separate pocket with the outside wall about the valve to be filled with a gel mass and it is suggested that radiopaque material can be added to the gel to make it responsive to X-ray. This device does not permit direct injection into the prosthesis but only into a separately constructed inner chamber which adds to the cost of manufacture.
It will be appreciated from the foregoing that the use of the injectable implant presents the ever present danger of damage to the prosthesis envelope by the injection needle that could render the prosthesis useless and require replacement by surgery. I have determined that this danger can be minimized and substantially eliminated so that direct injection into the prosthesis can be made accurately and safely. This is accomplished by not only precisely locating the perimeter of the valve but also and especially important in this procedure of precisely locating the center point thereof so that an accurate perpendicular attitude of the needle relative to the valve can be established to avoid contact with the prothesis wall. The preciseness in location is not possible in present prostheses where location of the valve depends upon palpation nor in those devices using radiopaque material such as disclosed in U.S. Pat. Nos. 3,919,724 and 4,253,201. The valves in these devices are provided with a pocket area filled with a gel mass which includes radiopaque material so that the valve can be identified under X-ray for insertion of the needle. However, it is well known from several studies that significant doses of radiation to the breast tissue may produce dysplastic or tumoral change within the breast and therefore the use of ultrasound for localization of the valve in place of X-ray is preferable since with ultrasound, there is an absence of ionizing radiation to the remaining breast tissue. In the present invention, the improvements for localizing the perimeter and center of the valve, as will later be pointed out, are particularly suitable to ultrasound localization and this is important because in valves with a homogeneous or consistent opaque area, the true dimensions of the valve in an anterior to posterior or front to back dimension cannot be truly appreciated. For this reason, with present devices, it is possible to advance the needle obliquely into the valve while under the impression that one is truly advancing perpendicular to the valve and thus pierce the prosthesis. For those prostheses using double envelopes, there are inherent difficulties in locating the inner envelope with the injection needle without contact and damage to the outer envelope particularly when the envelopes are collapsed to any degree and this is a disadvantage which I have also overcome as will appear.